46C-3 |
Effect of growing region and processing method on olive oil compositon in Palestine |
F. ABU DAGGA1, D. Hendricks2, and C. E. Carpenter2. (1) Chemistry, Arab American University Jenin, PO Box 240, Jenin, Palestine, Israel, (2) Nutrition and Food Sciences, Utah State University, UMC 8700, Logan, Utah, Logan, UT 84322 Olive oil is one of the most valuable agricultural commodities from Palestine where up to 30,000 metric tons are produced in good years. Up to half of the production is exported. Olive groves occupy 45 percent of all agricultural land. The objective of this study was to evaluate whether there is sufficient variation in composition of Palestinian olive oil to warrant a classification system. Two major factors were considered as possibly affecting composition. First, the geographical growing region, and second, the press technology used to extract the oil. Oil samples were collected representing 6 geographical areas (Bethlehem, Ramallah, Tulkarem, Nablus, Qabatiya and Jenin) and were obtained from 9 different presses (3 stone mills and 6 fully automatic). The samples were analyzed using classical methods for peroxide and free fatty acids and high-resolution gas chromatography for fatty acid distribution and for sterol profiles. Saturated, monounsaturated, polyunsaturated fatty acids and sterols content of the oil samples varied by growing region and pressing method. Saturated fatty acids (content 15.5 – 19.2 %) among the samples varied by 25 %, while monounsaturated fatty acids (content 68.9 – 74.4 %) only varied 8 %. Polyunsaturated acids (content 8.4 – 13.2 %) varied by 57 %. Total sterol content (cholesterol, campesterol, stigmasterol, clerosterol, b-sitosterol and avenasterols) varied among samples by over 80 %. The total sterol was 800-1500 mg per kg product with over 80% b-sitosterol. Neither growing location nor pressing methods had any effect on total free fatty acid (0.5-2.5 %) or peroxide values (18-30 meq per kg product). These results establish that olive oil from Palestine varies in composition by growing region and pressing method. Because composition is directly linked to oil quality and nutritional value, a classification system for Palestinian olive oil according to composition may be beneficial for producers, processors and consumers.
Session 46C, Food Chemistry: Lipids, antioxidants and emulsifiers
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